<!DOCTYPE html>

<svg width="200" height="200">
    <defs>
        <pattern id="pattern" patternUnits="userSpaceOnUse" width="40" height="40">
            <rect width="20" height="20" fill="white" x="0" y="0"></rect>
            <rect width="20" height="20" fill="blue" x="20" y="20"></rect>
        </pattern>
    </defs>
    <rect width="200" height="200" stroke="red" fill="url(#pattern)" />
</svg>
